Minnesota Democrat Al Franken made it official today. He announced his resignation from the Senate - this amid a growing number of complaints from women who say he touched them or tried to kiss them inappropriately. The accusations had been multiplying for weeks. And as NPR's Scott Detrow reports, Franken's Democratic colleagues finally decided they had to abandon a longtime ally.

SCOTT DETROW, BYLINE: Franken's fall from the top tier of Democratic politics was swift and sudden. When more women began speaking out against sexual misconduct this fall and began being taken seriously, Franken says he welcomed it. Then the accusations were about him. On the floor of the Senate today, Franken said he wanted to be respectful of the women accusing him.

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AL FRANKEN: I think that was the right thing to do. I also think it gave some people the false impression that I was admitting to doing things that in fact I haven't done. Some of the allegations against me are simply not true. Others I remember very differently.

DETROW: Fellow Democrats spoke out against Franken after the first wave of accusations. They called for an ethics investigation. But no one called on him to resign even as the number of complaints grew. The last one, though, was one too many. New York Democrat Kirsten Gillibrand was the first to call for him to resign, followed quickly by many other Democratic women than men. California Democrat Dianne Feinstein says the party is responding to what she's calling a huge cultural shift, leading more women to speak out.

DIANNE FEINSTEIN: And that unlike the past where there was a level of intimidation, that no longer exists. They will come forward, and they will indicate what happened to them.

DETROW: That doesn't mean Senate Democrats were happy when Franken took their advice to step down.

UNIDENTIFIED MAN: Step down own immediately.

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DETROW: In the Senate today, many lawmakers were like Wisconsin Democrat Tammy Baldwin - silent and stone-faced when asked for comment from reporters. Here's what Illinois Democrat Tammy Duckworth said she told Franken on the Senate floor.

TAMMY DUCKWORTH: I gave him a big hug and told him I love him and thanked him for what he's doing today.

DETROW: It's part of a political shift that saw House Minority Leader Nancy Pelosi go from calling Michigan Democrat John Conyers an icon to calling for his resignation over the course of about a week. Democrats have decided they can't protect or excuse away their own members if they're going to keep attacking Republicans for candidates like Roy Moore or, more broadly, if they're going to claim they're the party that represents women. So now Franken is ending a career that just months ago was on such an upward path that he had to deny questions about whether he would run for president.

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FRANKEN: It's very flattering. And no, I don't want to do that. What I - we got stuff to work on right now.

DETROW: Before the accusations began, Franken had a book on the national bestseller lists. He finished it just after the 2016 election, and it came out in May.

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FRANKEN: I write in the book - is, I don't know if Donald Trump will still be president when the - when you read this book.

DETROW: But Trump is still president, and now Franken is gone.

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FRANKEN: I of all people am aware that there is some irony in the fact that I am leaving while a man who has bragged on tape about his history of sexual assault sits in the Oval Office.

DETROW: Here's how Kirsten Gillibrand viewed that dynamic in the initial post calling for Franken to resign. She wrote, quote, "while it's true that his behavior is not the same as the criminal conduct alleged against Roy Moore or Harvey Weinstein or President Trump, it is still unquestionably wrong. It should not be tolerated by those of us who are privileged to work in public service." Enough Democrats agreed that Franken is now leaving the Senate. Scott Detrow, NPR News. Transcript provided by NPR, Copyright NPR.